trpl: Use infinite iterator in chain example with take

[puzza007]

No description provided.

[rust-highfive]

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[aochagavia]

cc @steveklabnik

[steveklabnik]

So, while it's true that you usually use unbounded iterators with take(), I'm not sure we actually explained them before this point. Can you look into that, please?

[puzza007]

Yeah they're explained in the previous section. https://github.com/rust-lang/rust/pull/25941/files#diff-f81dbe18693d6f4de2cd78b29a5ea670R284

[steveklabnik]

@puzza007 excellent, thank you!

[steveklabnik]

@bors: r+ rollup

[bors]

📌 Commit 5fefae6 has been approved by steveklabnik